Organic thin-film transistors (OTFTs) have attracted much attention in recent years as a low-cost alternative to amorphous silicon transistors for electronic applications. OTFTs are particularly suited for applications where large-area circuits (e.g., backplane electronics for large displays), desirable form factors and structural features (e.g., flexibility for e-paper), and affordability (e.g., ultra low cost for ubiquitous RFID tags) are essential. The key component of OTFTs is the semiconductor materials. Therefore, there is enormous interest in the development of new organic semiconductors for OTFT applications.
Organic semiconductors are typically based on: (1) acenes such as tetracene, pentacene and their derivatives, (2) thiophenes such as oligothiophenes and polythiophenes, (3) fused-ring thiophene-aromatics and thiophene-vinylene/arylene derivatives. Most of these semiconductors are either insoluble or are sensitive to air, and may therefore not be suitable for low-cost OTFT applications. Therefore, there is a need addressed by embodiments of the present invention to develop new organic semiconductor compounds that can be processed in air for manufacturing low-cost OTFTs.
Moreover, it is desirable that the charge carrier mobility of OTFTs approach that of the amorphous silicon transistor. There is therefore a need addressed by embodiments of the present invention to provide sufficiently high charge carrier mobility for OTFTs.
The following documents provide background information:
Christos D. Dimitrakopoulos et al., “Organic Thin Film Transistors for Large Area Electronics,” Adv. Mater., Vol. 14, No. 2, pp. 99-117 (2002).
Salem Wakim et al., “Organic Microelectronics: Design, Synthesis, and Characterization of 6,12-Dimethylindolo[3,2-b]Carbazoles,” Chem. Mater. Vol. 16, No. 23, pp. 4386-4388 (published on web Jul. 7, 2004).
Nan-Xing Hu et al., “5-11-Dihydro-5,11-di-1-naphthylindolo[3,2-b]carbazole: Atropisomerism in a Novel Hole-Transport Molecule for Organic Light-Emitting Diodes,” J. Am. Chem. Soc., Vol. 121, pp. 5097-5098 (1999).
Hu et al., U.S. Pat. No. 5,942,340.
Hu et al., U.S. Pat. No. 5,952,115.
Hu et al., U.S. Pat. No. 5,843,607.